U.S. patent number 5,175,928 [Application Number 07/758,221] was granted by the patent office on 1993-01-05 for method of manufacturing an electrical connection assembly.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Dimitry G. Grabbe.
United States Patent |
5,175,928 |
Grabbe |
January 5, 1993 |
Method of manufacturing an electrical connection assembly
Abstract
An electrical connector assembly having a metal or metallized
plastic housing block (10) with contact members (26) contained
within channels (12) in the block (10). The metallic housing block
(10) provides a shield to eliminate cross-talk between the contact
members (26). The contact members (26) are directly coated with a
dielectric material, except where they perform an electrical
contact function, to insulate them from the metallic housing block
(10).
Inventors: |
Grabbe; Dimitry G. (Middletown,
PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
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Family
ID: |
27065050 |
Appl.
No.: |
07/758,221 |
Filed: |
September 5, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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536149 |
Jun 8, 1990 |
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Current U.S.
Class: |
29/884; 29/885;
439/607.01; 439/607.06; 439/885; 439/886 |
Current CPC
Class: |
H01R
12/727 (20130101); H01R 13/03 (20130101); Y10T
29/49224 (20150115); Y10T 29/49222 (20150115); H01R
12/724 (20130101) |
Current International
Class: |
H01R
13/03 (20060101); H01R 043/16 () |
Field of
Search: |
;29/883,884,885
;439/885,886 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0005983 |
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Dec 1979 |
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EP |
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1971197 |
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May 1971 |
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JP |
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Primary Examiner: Arbes; Carl J.
Attorney, Agent or Firm: Trygg; James M. Wolstoncroft; Bruce
J.
Parent Case Text
This application is a Continuation of application Ser. No.
07/536,149 filed Jun. 8, 1990, now abandoned.
Claims
I claim:
1. A method of manufacturing an electrical connector assembly,
comprising the steps of:
providing a metallic housing having a plurality of channels opening
onto a first surface and a second surface of said housing;
providing a plurality of metal contact members adapted for
containment each within a respective one of said housing channels,
each of said contact members having a first contact portion, a
second contact portion and a body portion, said first and second
contact portion of each of said contact members being exposed at
said housing first and second surfaces, respectively, when said
each contact member is contained within the respective housing
channel, the step of providing a plurality of metal contact members
including stamping and forming from sheet stock said plurality of
metal contact members attached to a carrier strip;
depositing on at least the body portion of said each contact member
while attached to said carrier strip a layer of dielectric material
so as to insulate said each contact member from said housing;
removing said plurality of contact members from said carrier strip;
and
installing said plurality of contact members in the respective
housing channels.
2. The method according to claim 1 wherein the step of depositing
includes the step of dipping said plurality of contact members into
a dielectric-carrying solution.
3. The method according to claim 1 wherein the step of depositing
includes an electrophoretic process.
4. The method according to claim 1 wherein the step of depositing
includes the step of spraying said plurality of contact
members.
5. The method according to claim 1 wherein the step of depositing
includes a process of electrostatic powder deposition and
fusing.
6. The method according to claim 1 wherein the step of depositing
includes the step of spraying said plurality of contact members
with a mixture of polytetrafluoroethylene with polyimid.
7. The method according to claim 1 wherein the step of depositing
includes the step of electrophoretic deposition with aluminum
oxide.
8. The method according to claim 1 wherein the step of depositing
includes the step of electrophoretic deposition with barium
titanate.
9. The method according to claim 1 wherein the step of depositing
includes the step of sputtering.
10. The method according to claim 1 wherein the step of depositing
includes the step of ion beam deposition.
11. The method according to claim 6 wherein said first contact
portion is a female receptacle portion and further including the
step of:
inserting a deformable member in said female receptacle portion
prior to the step of depositing, said deformable member conforming
to the interior walls of said female receptacle portion so that
said dielectric material is not subsequently deposited on said
walls.
12. The method according to claim 1 further including the step of
bending said each contact member after the step of depositing and
wherein the step of depositing avoids placing said layer of
dielectric material on any part of said each contact member which
is subsequently bent.
Description
BACKGROUND OF THE INVENTION
This invention relates to electrical connector assemblies and, more
particularly, to electrical connector assemblies of densely packed
contact members capable of passing fast rise time pulses without
cross-talk between adjacent contact members.
There presently exists in the marketplace a large family of
electrical connectors which have a thick plastic housing and long
channels, or holes, into which either male or female contact
members are inserted. These connectors are typically utilized for
mounting and connecting daughter printed circuit boards onto mother
printed circuit boards and represent a major multi-million dollar
investment in tooling for the housings, the contact members and the
assembly machinery. In general, when signals passed by the
connector assembly have two nanosecond or slower rise times, these
connector assemblies have proven to provide satisfactory
performance. However, the industry is moving to much faster rise
times and, with the shortening of the rise times this tends to
increase the cross-talk between adjacent contact members. In the
past, to eliminate such cross-talk, signal-carrying contact members
have been surrounded by between four and eight grounded contact
members which act as a shield. A major problem with this approach
is that as the complexity of the electronics mounted to the printed
circuit board increases, there is insufficient room for the extra
grounded contact members. Accordingly, it is an object of the
present invention to provide an electrical connector assembly which
eliminates cross-talk between signal-carrying contact members
without the use of grounded shielding contact members.
One approach to solving this problem is detailed in my U.S. Pat.
No. 4,906,194, where I disclose a high density connector assembly
for an integrated circuit chip carrier which includes a stack of
metallic plates having apertures which form chambers for holding
contact members therein. The stack of plates provides a ground
shield around each of the contact members to prevent cross-talk
therebetween. To insulate the plates from the contact members, the
plates are coated with an insulating layer of dielectric material.
This method of constructing a connector housing block, while
suitable for relatively thin connectors of the type disclosed in
the referenced patent, is economically prohibitive for larger
circuit board to circuit board connectors which frequently have a
thickness greater than one-half inch.
It is therefore a further object of the present invention to
provide a larger size connector assembly which provides cross-talk
shielding and which salvages as much as possible the tooling,
assembly machines, etc., which already exist for the present
connector assembly which it replaces.
SUMMARY OF THE INVENTION
The foregoing and additional objects are attained in accordance
with the principles of this invention by providing an electrical
connector assembly including a plurality of metal contact members
each of which has a first contact portion, a second contact
portion, and a body portion, a metal or metallized plastic housing
having a plurality of channels each adapted to contain therein at
least the body portion of a respective one of the plurality of
contact members, and means separate from the housing for insulating
each of the contact members from the metal housing.
In accordance with an aspect of this invention, the insulating
means comprises a coating of dielectric material on the body
portion of each of the contact members.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing will be more readily apparent upon reading the
following description in conjunction with the drawings in which
like elements in different figures thereof have the same reference
numeral and wherein:
FIG. 1 is a sectioned perspective view of the housing of an
electrical connector assembly to which the principles of this
invention may be applied;
FIGS. 2A-2D illustrate various steps in the formation of an
illustrative contact member for use with the housing of FIG. 1;
and
FIG. 3 is sectional view of the housing of FIG. 1 having installed
therein a plurality of the contact members of FIGS. 2A-2D.
DETAILED DESCRIPTION
An illustrative connector housing block of the type with which the
present invention is concerned is illustrated in FIG. 1. As shown
therein, the connector housing block 10 has a plurality of
channels, or passages, 12 extending through the block 10 and
opening out onto surfaces 14, 16. The channels 12 are arranged in
an array of rows and columns, with the rows of channels 12 being
separated by interior longitudinal walls 18 and the columns of
channels 12 being separated by transverse walls 20. The channels 12
open out into slots 22 which are defined by adjacent transverse
walls 20 and free ends 24 of longitudinal walls 18.
According to the present invention, the connector housing block 10
is either formed of metal, such as for example, by an aluminum or
zinc die casting process, or alternatively the housing block 10 is
formed of plastic which is subsequently metallized. It is
preferable to use a metallized plastic housing if the tooling for
the housing already exists. The metallic connector housing block 10
then inherently provides a ground shield around each of the contact
members in a channel 12, which allows a high density of contact
members without cross-talk therebetween.
However, since the contact members are themselves made of metal,
some means must be provided for insulating the contact members from
the metallic connector housing block 10. There are several ways of
surrounding each of the contact members with an insulating
dielectric. One way is to plate the dielectric directly on the
interior walls of the channels 12. This poses a problem since all
of the available plating methods, such as dipping,
electrostatically spraying and fusing powders, spray painting, or
electrophoretic deposition, are unable to produce a uniform
thickness of deposition of dielectric at the mouths and at the
centers of the channels 12. (It is to be noted however that a
uniform thickness of metal can be obtained by an electroless
process to form a metallized plastic housing.) A second way of
providing insulation is to insert a prefabricated dielectric sleeve
into each of the channels 12, the contact members then being
inserted within the sleeve. This can be a viable approach for those
cases where there is sufficient room available to do so, since such
a sleeve would have to be of sufficient mechanical strength, and
therefore bulk, to withstand handling and insertion into the
housing.
In accordance with the principles of this invention, a third
approach is proposed. This inventive approach is to have an
existing contact member, as presently used in an existing connector
housing block, coated directly with a dielectric material. The
portions of the contact member which perform the mechanical
function, such as a structural member or a spring, can be coated on
all surfaces. The portions of the contact member which perform
electrical contacting functions must remain free of any dielectric
material.
FIGS. 2A-2D illustrate steps in the formation of a contact member
26 for use with the connector housing block 10 of FIG. 1, and FIG.
3 illustrates the installation of the contact members 26 in the
channels 12 of the block 10. It is to be noted that each of the
contact members 26 has a male contact portion and a female contact
portion, but the principles of this invention may be applied to any
other type contact member such as one with two male contact
portions or one with two female contact portions.
Typically, contact members for electrical connector assemblies are
manufactured by stamping and forming from flat metal sheet stock.
FIG. 2A shows the contact member 26 after being stamped but prior
to being formed, while still being attached to parallel carrier
strips 28, as is conventional in the art. FIG. 2B shows the contact
members 26 still attached to the carrier strips 28 but after being
formed, with FIG. 2C being an end view of FIG. 2B. FIG. 2D shows
the completed contact member 26 after removal from the carrier
strips 28 and after it has assumed its final form upon installation
in the block 10.
Thus, the illustrative contact member 26 includes female receptacle
portion 30, intermediate body portion 32 and male contact portion
34. The female receptacle portion 30 includes four resilient beams
36 defining a post receiving space 38 therebetween. As is clear
from FIG. 3, the contact members 26 are formed with different
lengths for the male contact portion 34 to accommodate the location
and length of the channels 12 in the block 10. In all other
respects, each contact member 26 is identical to another contact
member 26.
As is clear from FIG. 3, when each of the contact members 26 is
coated with an insulative dielectric material, the distal end of
the male contact portion 34, extending a distance "A" from the end,
should be free of the dielectric coating so that it can perform its
electrical contact function. This end of the contact member 26 does
not touch the block 10. Similarly, the portions of the resilient
beams 36 which form the interior walls of the post receiving space
38 must be free of the dielectric coating so that they too may
perform their electrical contact function. The body portion 32 of
the contact member 26, the remainder of the male contact portion
34, and the exteriorly facing portions of the resilient beams 36
should all have the dielectric coating thereon because they may be
in contact with the metal of the block 10.
Application of the dielectric material can be accomplished in a
number of different ways such as, for example, by spraying,
dipping, electrostatic powder deposition and fusing, and
electrophoretic deposition. Each of these processes permits a
selection of materials with different dielectric properties. For
example, spraying with a combination of polytetrafluoroethylene
(such as teflon) with a small amount of polyimid produces a coating
with very low dielectric constant. On the other hand,
electrophoretic deposition using a material such as, for example,
aluminum oxide or barium titanate produces a coating with very high
dielectric constant. The choice of material or process to use may
be governed more by the required impedance considerations, given a
set of available dimensions, than any other considerations. Other
processes for coating the contact member 26 include sputtering and
ion beam deposition, which may not be economically feasible.
Since a typical preferred dielectric material, such as aluminum
oxide, is relatively hard, if it were applied to the contact
members 26 while they are in the form shown in FIG. 2A continued
formation of the contact members as shown in FIGS. 2B and 2C would
result in the dielectric material breaking at the fold points and
subsequently flaking off the contact members 26. It is therefore
preferred that when the contact members are in the form shown in
FIGS. 2B and 2C, that they be held by the upper carrier strip 28
and dipped into a dielectric-carrying solution for deposition, such
as by an electrophoretic process. This dipping should be to the
point 42 (FIG. 2A) so that the distal end of the male contact
portion 34, extending the distance "A" from the extremity, is free
of the dielectric coating. As shown in FIG. 3, the distance "A"
along the male contact portion 34 is of sufficient length that it
passes the bend point of the portion 34 but stops short of where
the contact member 26 touches a metallic wall of the housing block
10. Thus, all bending which occurs after the dielectric coating is
applied takes place in a region which is free of the dielectric
coating so that no flaking occurs. Since it is desired that the
dielectric coating not cover the portions of the resilient beams 36
which form the interior walls of the post receiving space 38, prior
to the dipping a plastic pin is inserted into the post receiving
space 38 of each of the contact members 26. Since the dielectric
coating will be applied to all areas of the post receiving space 38
which are not in physical contact with the plastic pin, it is
preferred that the plastic of the pin be soft enough that it
deforms slightly so as to conform as much as possible to the walls
formed by the resilient beams 36.
The aforedescribed invention possesses a number of advantages.
Thus, by forming the connector housing block of metal or metallized
plastic, a shield around each of the contact members is inherently
provided, thereby eliminating the cross-talk between contact
members. Also, forming the connector housing block and the contact
members without change from a prior configuration results in use of
the same tooling and assembling machinery, thereby avoiding
unnecessary additional expense. Further, adding the insulation
directly to the contact members results in minimal incremental
cost.
Accordingly, there has been disclosed an improved electrical
connector assembly of densely packed contact members capable of
passing fast rise time pulses without cross-talk between adjacent
contact members. While an illustrative embodiment has been
disclosed, it will be apparent to those skilled in the art that
various modifications to that embodiment may be made and it is only
intended that the scope of this invention be limited by the
appended claims.
* * * * *